Effects of curing units and staining solutions on the color susceptibility of a microhybrid composite resin

Background/purpose: To examine the effect of different light-curing units and staining solutions on a microhybrid composite resin. Materials and methods: Two shades (A3 and B3) of a light-activated composite (Ecusit resin) were cured in polytetrafluoroethylene disk rings (45 each) using 3 different light-curing units: 1) a quartz-tungsten-halogen (QTH) unit, 2) a light-emitting diode (LED) unit, and 3) a plasma-arc curing (PAC) unit. Two beverages (coffee and tea) were used as staining solutions, and distilled water was used as a control. Evaluations were made after 1, 7, 15, and 30 days by means of reflectance spectrophotometry. Results: Data were statistically analyzed using one-way analysis of variance, and post-hoc comparisons were made using Tukey's test with a significance level of 5%. A Kruskal-Wallis multiple-comparison test was performed to evaluate Delta E* values among water, tea, and coffee immersion with 2 shades of the composite. Statistically significant color changes were observed between water and coffee, and tea and coffee for different time periods; whereas no difference was seen between water and tea in LED-cured A3 Ecusit resin specimens after either 1 or 15 days of immersion, those cured by PAC after 15 days of immersion, or in LED-cured B3 Ecusit resin specimens after 7 days. Conclusions: PAC-cured Ecusit resin specimens showed significantly higher discoloration than the other specimens. The staining solutions produced discoloration, while water caused the least changes. Copyright (C) 2011, Association for Dental Sciences of the Republic of China. Published by Elsevier Taiwan LLC. All rights reserved.